And 4K is not new.... GoPro has had it for a year now..... It was inevitable that someone would come out with it in a DSLR or a mirrorless camera, Panasonic just happens to be the first. Others will follow. Today it is a niche, tomorrow it will be a standard feature.We need to stop using the GoPro example - at only 15fps, it's still not viable video.
Yes, it's inevitable for 4K video to show up in something, just like it's inevitable that Canon, Nikon, etc. will keep raising the megapixel count in their cameras. However, Canon has a habit of reserving better video features for higher-end cameras to avoid cannibalizing their own products, e.g. the 1DC having clean HDMI, but not the 1DX. Certain other companies (I'm looking at you, Nikon) have nothing to cannibalize and might beat Canon to the 4K-in-a-DSLR milestone, just like they technically beat Canon to clean HDMI out with the D800 vs. the 5D3, and Canon had to play catch-up.